Over the years considerable work has been devoted to additives for controlling (preventing or reducing) deposit formation in the fuel induction systems of spark-ignition internal combustion engines. In particular, additives that can effectively control fuel injector deposits, intake valve deposits and combustion chamber deposits represent the focal point of considerable research activities in the field and despite these efforts, further improvements are desired.
Direct injection gasoline (DIG) technology is currently on a steep developmental curve because of its high potential for improved fuel economy and power. Environmentally, the fuel economy benefits translate directly into lower carbon dioxide emissions, a greenhouse gas that could contribute to possible global warming.
Conventional multi-port injection (MPI) engines form a homogeneous pre-mixture of gasoline and air by injecting gasoline into the intake port, while a direct injection gasoline engine injects gasoline directly into the combustion chamber like a diesel engine so that it becomes possible to form a stratified fuel mixture which contains greater than the stoichiometric amount of fuel in the neighborhood of the spark plug but highly lean in the entire combustion chamber. Due to the formation of such a stratified fuel mixture, combustion with the overall highly lean mixture can be achieved, leading to an improvement in fuel consumption approaching that of a diesel engine.
Injection timing is controlled to match load conditions. The fuel control provides combustion of an ultra lean mixture of gasoline and air for higher fuel efficiency than diesel engines. Also, a compression ratio of about 12.0 compared to that of about 10.5 for multi port injection engines delivers higher volumetric efficiency and response, surpassing conventional MPI engine performance.
There are a number of technical issues to be resolved with DIG technology, and one of them is injector performance with different gasoline fuels on the world market. Being located in the combustion chamber, DIG injectors are exposed to a much harsher environment than conventional spark-ignition engines with port fuel injectors (PFI). This more severe environment can accelerate fuel degradation and oxidation resulting in increased deposits.
DIG technology promises about a third less carbon dioxide emissions than comparable conventional multi-port injection. This is achieved with a 10–15% improvement in fuel consumption when operating in the homogeneous mode, and up to 35% when operating in the lean stratified mode. Fuel economy benefits also translate into fossil energy conservation and savings for the consumer. In addition, the DIG operation platform facilitates up to a 10% power increase for the same fuel burned in the equivalent MPI configuration.
Current generation DIG technologies have experienced deposit problems. Areas of concern include fuel rails, injectors, combustion chamber (CCD), crankcase soot loadings, and intake valves (IVD).
Fuel related deposits in DIG engines are an issue of current interest since this technology is now commercial in Japan and Europe. Fuel injector performance is at the forefront of this issue because the DIG combustion system relies heavily on fuel spray consistency to realize its advantages in fuel economy and power, and to minimize exhaust emissions. A consistent spray pattern enables more precise electronic control of the combustion event and the exhaust after-treatment system.
There is a desire in the petroleum industry to produce a fuel suitable for use in both MPI and DIG engines, that is a fuel having effective IVD control for a MPI engine as well as a fuel having effective injector deposit control suitable for a DIG engine. Additives useful in reducing or controlling intake valve deposits in a MPI engine may have little or no effect or even an adverse effect in controlling or reducing injector deposits in a DIG engine. Likewise, additives useful in controlling or reducing injector deposits in a DIG engine may have little or no effect or even an adverse effect in controlling or reducing intake valve deposits in a MPI engine. An object of the present invention is to provide fuel compositions that provide effective injector deposit control in DIG engines as well as providing fuel compositions which provide effective deposit control in both MPI and DIG engines.
There are references teaching fuel compositions containing amines and amine derivatives compounds, for example, U.S. Pat. Nos. 5,643,951; 5,725,612 and 6,176,886. However, none of these references teach the use of fuel compositions containing the amine compounds and derivatives of the present invention in direct injection gasoline engines or the impact such compounds have on deposits in these engines.